1. Field of the Invention
This invention relates to an ink feeding method and ink feeding apparatus for feeding a preset ink after making prints having a first image and before making prints having a second image.
2. Description of the Related Art
When making a plurality of prints continuously with a printing machine, the quantity of ink corresponding to the image of preceding prints remains on the ink rollers of the printing machine. Thus, for continuing to make prints having a different image, a presetting operation is carried out for adjusting a thickness of ink film on the ink rollers to a size corresponding to the image to be printed next. In this presetting operation, for example, the thickness of ink film on the ink rollers is uniformed by removing the ink, and then the film thickness is adjusted to the image to be printed next.
However, when the presetting operation is carried out in the two stages as above, the ink is consumed in a wasteful quantity, and the operation takes a long time also.
Further, ink presetting methods have been proposed, in which an image printed previously is measured, and a thickness of ink film is adjusted in time of presetting based on measured values (Japanese Unexamined Patent Publications No. 1989-208135 and No. 2000-108308).
However, one of the above methods is a technique relating to a proof press, which estimates a remaining quantity of ink from the number of sheets printed after the latest ink feeding event. Such a technique is unsuitable to a printing machine that feeds ink continuously.
The other of the above methods determines beforehand a correspondence between actual ink key opening degree and printing area ratio in an excellent printing state, and merely uses such data in subsequent printing operations. Thus, a change in the operating state or printing conditions of the printing machine could render such data obtained from an actual situation unusable. In addition, the thickness of remaining ink film is variable with the state in which a printing operation is ended.